We conducted the first cost-benefit analysis of a federally financed, comprehensive early childhood program. The Title I Chicago Child-Parent Centers are located in public schools and provide educational and family support services to low-income children from ages 3 to 9. Using data from a cohort of children born in 1980 who participate in the Chicago Longitudinal Study, findings indicated that the measured and projected economic benefits of preschool participation, school-age participation, and extended program participation exceeded costs. The preschool program provided a return to society of $7.14 per dollar invested by increasing economic well-being and tax revenues, and by reducing public expenditures for remedial education, criminal justice treatment, and crime victims. The extended intervention program (4 to 6 years of participation) provided a return to society of $6.11 per dollar invested while the school-age program yielded a return of $1.66 per dollar invested. Economic benefits to the general public, exclusive of individual earnings, also exceeded costs for all three levels of program participation. Findings demonstrate the cost-effectiveness of public early childhood programs. Appended is "Breakdown of Benefits and Costs for Estimating Economic Returns of the Chicago Child-Parent Centers."